1. Field of the Invention
The present disclosure relates to an optical pickup device and an optical pickup unit, and also relates to a data streamer apparatus including the optical pickup device.
2. Description of the Related Art
An optical pickup device for use in a conventional optical disc drive includes a laser that functions as a light source and a lens actuator that drives an objective lens in focusing and tracking directions. The lens actuator includes a base portion which is fixed onto the body of the optical pickup device, a movable portion that mounts the objective lens thereon and that can move in the focusing and tracking directions, and an elastic supporting member which couples elastically the movable portion to the base portion. Coils are attached to the movable portion, and a magnet is attached to the base portion. By adjusting the direction and amount of the current flowing through the coils of the movable portion, magnetic force is applied to the coils within the magnetic field generated by the magnet, and the position and orientation of the movable portion can be controlled. The objective lens can have its position changed both perpendicularly to the surface of a given storage medium (i.e., in the focusing direction) and parallel to the surface of the storage medium and perpendicularly to the tracks on the storage medium (i.e., in the tracking direction). In order to move the lens in these two directions, a focus coil that produces force in the focusing direction and a tracking coil that produces force in the tracking direction are separately provided for the movable portion. And the elastic supporting member produces restitution force against these forces.
The elastic supporting member may be a wire, for example, the length of which is determined by the space that can be left in the optical pickup device and the power that needs to be supplied to move the movable portion. The wire usually has a length of 10 mm to 20 mm. And the wire is secured to the movable portion at two points that are close to both ends thereof in the tracking direction. That is why the objective lens is arranged inside of the region that is surrounded with the wire. Also, in order to drive the movable portion with good stability in both the focusing and tracking directions, the actuator may be designed so that the center of mass of the movable portion agrees with the center of the driving force in each of those two directions. Such a technique is disclosed in Japanese Laid-Open Patent Publication No. 2002-50062, for example.
Meanwhile, an optical tape apparatus (which is also called a “data streamer apparatus”) that writes data on an optical tape is being developed as a storage device with a huge storage capacity. An example of such an optical tape apparatus is disclosed in Japanese Laid-Open Patent Publication No. 2006-286070.
Recently, it has become more and more necessary to further reduce the size of an optical pickup device for optical discs perpendicularly to the disc surface. As for directions that are parallel to the disc surface, i.e., the track running direction and the tracking direction, the arrangement of the optical disc drive and optical pickup device can be modified within the space that is defined by projecting the overall area occupied by the optical disc. That is why as far as optical discs are concerned, plenty of space is left to arrange the wire and the objective lens in the objective lens actuator in those directions that are parallel to the disc surface.
On the other hand, in an optical tape storage device, only a narrow space is left to arrange the pickup device with respect to the tape running direction.
It is therefore an object of the present invention to provide an optical pickup device that can reduce the space to be left in the tape running direction compared to conventional ones.